Compositions and methods for assembly and stabilization of antibody Fv fragments via antiparallel heterogeneous coiled-coil peptide regions and uses thereof

ABSTRACT

Compositions and methods using antiparallel heterogeneous α-helical coiled-coil (AHEC) regions for the linkage and stabilization of antibody Fv domains are provided.

[0001] This application claims the benefit of priority from U.S. Provisional Application Serial No. 60/354,376, filed Feb. 5, 2002, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to the use of antiparallel heterogeneous dimeric, trimeric and tetrameric coiled-coil (AHEC) peptide regions, specifically designed de novo, selected from libraries, or derived from nature, for the assembly and stabilization of antibody Fv fragments in a predetermined manner. Use of the AHEC region permits the assembly of antibody fragments into defined multimeric complexes, wherein the essential feature of the AHEC is the stabilization of two antibody Fv domains and their possible linkage to a different functional group or polypeptide chain, including a further pair of antibody Fv domains. The two antibody Fv domains are expressed as N-terminal fusion proteins in which the C-terminal fusion partner is one of the AHEC complex peptides. When assembled, the AHEC complex holds the C-terminals of the two Fv domains at each end of the AHEC complex. The distance between the two AHEC fusion ends is optimized to be similar to that found in full-length antibodies at around 35-45 Å. The use of AHEC peptides that form trimeric or tetrameric complexes allows the addition of further functional proteins, protein fragments, peptides or chemically modified peptides to the AHEC-antibody Fv complex. Multimeric complexes joined via AHEC regions are useful in a number of different areas including, but not limited to, research, industry and healthcare.

BACKGROUND OF THE INVENTION

[0003] Various coiled-coil multimerization regions for the assembly of proteins or protein fragments have been described.

[0004] WO 98/56906 describes tetranectin-derived polypeptides capable of forming stable trimers. These complexes comprise the tetranectin trimerization region as the trimerizing structural element for other protein and chemical entities. WO 95/31540 describes a trimerization module derived from collectin coiled-coil structures and its application to the engineering of artificially trimerized proteins. Polypeptides comprising a collectin neck region that are able to trimerize are also described in U.S. Pat. No. 6,190,886.

[0005] Coiled-coil multimerization regions have also been used in various contexts in relation to the production and use of recombinant antibodies. U.S. Pat. No. 5,643,731 describes uses for a pair of leucine-zipper peptides, preferably v-fos and c-jun, for in vitro diagnosis, in particular for the immunochemical detection and determination of an analyte in a biological fluid. In one method, the first leucine-zipper peptide is immobilized by attaching it to a solid support, the second leucine-zipper peptide is coupled to a specific binding partner for the analyte, and the amount of analyte bound to the binding partner is determined. U.S. Pat. No. 6,165,335 describes a biosensor apparatus for detecting a binding event between a ligand and its receptor. The apparatus includes a biosensor surface and surface-bound two-subunit heterodimer complexes composed of preferably oppositely charged peptides that together form an α-helical coiled-coil. The first peptide is attached to the biosensor surface, and the second peptide carries the ligand, accessible for binding by a ligand-binding agent. Binding of the ligand-binding agent to the surface-bound ligand is then detected in a suitable manner. A ligand-specific biosensor surface can readily be prepared from a universal template containing the first charged peptide, by addition of a selected ligand attached to the second peptide.

[0006] U.S. Pat. No. 5,932,448 describes methods for producing and using bispecific antibodies formed by leucine zippers. U.S. Pat. No. 5,837,242 describes polypeptides consisting of a first domain comprising a binding region of an immunoglobulin heavy-chain variable region, and a second domain comprising a binding region of an immunoglobulin light-chain variable region, the domains being linked but incapable of associating with each other to form an antigen binding site. These polypeptides are associated to form antigen-binding multimers, such as dimers, which may be multivalent or have multispecificity. The domains may be linked by a short peptide linker or may be joined directly together. Bispecific dimers may have longer linkers. Methods of preparation of polypeptides and multimers and diverse repertoires thereof, and their display on the surface of bacteriophage for easy selection of interest, are described.

[0007] The use of parallel helix-stabilized antibody fragments is also disclosed by Arndt et al. (J. Mol. Biol. 2001 312:221-228). The production of recombinant single chain antibody Fv fragments has also become well established since its inception over 10 years ago (Bird et al. Science 1988 242:423-426; Huston et al. Proc. Natl Acad. Sci. USA 1988 85:5879-5883).

[0008] A trimeric AHEC region can be derived from the repeated domains of spectrin. Spectrin, also referred to as fodrin, is a common component of cytoskeletal structures associated with cell membranes in metazoan organisms (Shenk, M. A. and Steele, R. E. Trends Biochem Sci. 1993 18:459-463). Electron microscopic studies of spectrin have revealed a flexible elongated molecule composed of two loosely intertwined antiparallel strands that appear to be tightly associated at both ends (Shotton et al. J. Mol. Biol. 1979 131:303-329). Each of these strands contains two homologous alpha and beta chains that associate into tetramers through a head-to-head interaction. The elongated protein chains of the spectrin family contain tandemly repeated segments, each segment doubling back on itself into a S-shape containing three interacting α-helical regions. The crystal structure of the repetitive segment of spectrin is taught by Yan et al. (Science 1993 262:2027-2030). The three-dimensional structure in solution of a chicken-brain spectrin repeat determined by NMR spectroscopy and distance geometry-simulated annealing calculations is taught by Pascual et al. (J. Mol. Biol. 1997 273:740-751).

[0009] The use of spectrin as a joining component of two or more effector molecules is described in U.S. Pat. No. 5,997,861. U.S. Pat. No. 6,303,317 teaches the use of coiled-coil region peptides such as the coiled-coil region of spectrin as probes to identify target polypeptides.

[0010] AHEC complexes may also be designed de novo. The ability to select for dimeric, trimeric or tetrameric complexes has been taught in previous publications (Zhou et al. Biochemistry 1993 32:3178-3187; Harbury et al. Science 1993 262:1401-1407; Monera et al. Protein Eng. 1996 9:353-363). Selecting between parallel or anti-parallel dimeric coiled-coil formation has been taught in a number of articles (Myszka, D. G. and Chaiken, I. M. Biochemistry 1994 33:2363-2372; Monera et al. Biochemistry 1994 33:3862-3871; Monera et al. J. Biol. Chem.1993 268:19218-19227; Oakley, M. G. and Kim, P. S. Biochemistry 1998 37:12603-12610; Betz et al. Biochemistry 1997 36:2450-2458; Monera et al. J. Biol. Chem. 1996 271:3995-4001; McClain et al. J. Am. Chem. Soc. 2001 123:3151-3152). Selection of heterogeneous coiled-coil complexes has also been examined (Nautiyal et al. Biochemistry 1995 34:11645-11651; McClain et al. J. Am. Chem. Soc. 2001 123:3151-3152). The effect of cysteine position on interchain disulfide linkage has been taught for two-stranded α-helical coiled coils (Zhou et al. Biochemistry 1993 32:3178-3187).

SUMMARY OF THE INVENTION

[0011] An object of the present invention is to provide compositions and methods for the assembly of a pair of Fv antibody fragments alone or with a protein, protein fragment, peptide or chemical in a defined manner by attaching a specific AHEC peptide to each component to be assembled. The attached antibody Fv fragments alone or with a protein, protein fragment, peptide or chemical associate into antiparallel heterogeneous dimeric, trimeric or tetrameric coiled coils, thus assembling the components into a non-naturally occurring oligomer.

[0012] Another object of the present invention is to provide compositions and methods wherein one or more cysteine residues are placed within or near the AHEC region to form interchain disulfide bridges, covalently linking two of the AHEC peptide chains as well as their attached proteins, protein fragments, peptides or chemicals, and thus stabilizing the complex, once formed by non-covalent interaction, by covalent crosslinkage.

[0013] Another object of the present invention is to provide compositions and methods using these AHEC regions to covalently or non-covalently attach proteins, protein fragments, peptides or chemical complexes to a surface and or solid support via an AHEC region.

DESCRIPTION OF THE FIGURES

[0014]FIG. 1 provides several nonlimiting examples of non-naturally occurring multimeric proteins derived from the present invention, particularly those derived from antibody Fv fragments, where the AHEC region is used to attach other functional units. FIG. 1(a) shows how AHEC complexes may be used in phage display of Fv antibody fragments; FIG. 1(b) shows the possibility of associating a His-tag enabling the complex to bind to nickel chelating columns; FIG. 1(c) shows how an AHEC region can be used to attach inert molecules such as poly(ethylene glycol) (PEG); and FIG. 1(d) shows specific immobilization to a surface via a linking molecule containing a peptide capable of forming part of an AHEC region.

[0015]FIG. 2(a) is an overview of the structure of a single-chain left-handed antiparallel triple-helical coiled-coil spectrin repeat domain. The figure is derived from the structure determined by Pascual et al. (J. Mol. Biol. 1997 273:740-751). FIG. 2(b) shows a subdivision of a spectrin repeat into the three separate chains (A, B and C) that make up an AHEC complex.

[0016]FIG. 3 shows the expression vector pG31018 derived from a pET20b(+) expression vector (Novagene). The vector contains DNA encoding the light-chain Fv domain of the anti-tetanus toxoid antibody HYB 278-14, followed by an AHECa region and finally by an affinity tag consisting of six histidine residues. The DNA sequence is shown in lower case (SEQ ID NO:1) and the derived amino-acid sequence in the upper case single letter code (SEQ ID NO:2). Relevant regions are marked in bold with an explanation in italics above.

[0017]FIG. 4 shows the expression vector pG31020 derived from pG31018 in which the codon for valine 122 has been mutated to one for cysteine (underlined). The DNA sequence is shown in lower case (SEQ ID NO:3) and the derived amino-acid sequence in the upper case single letter code (SEQ ID NO:4). Relevant regions are marked in bold with an explanation in italics above.

[0018]FIG. 5 shows the expression vector pG31025 derived from a pET20b(+) expression vector (Novagene) and containing DNA encoding a pe1B leader peptide followed by a factor Xa cleavage site, the heavy-chain Fv domain of the anti-tetanus toxoid antibody HYB 278-14, an AHECb region, and finally an affinity tag consisting of six histidine residues. The DNA sequence is shown in lower case (SEQ ID NO:5) and the derived amino-acid sequence in the upper case single letter code (SEQ ID NO:6). Relevant regions are marked in bold with an explanation in italics above.

[0019]FIG. 6 shows the expression vector pG31030 derived from pG31025 in which the codon for valine 176 has been mutated to one for cysteine (underlined). The DNA sequence is shown in lower case (SEQ ID NO:7) and the derived amino-acid sequence in upper case single letter code (SEQ ID NO:8). Relevant regions are marked in bold with an explanation in italics above.

[0020]FIG. 7 shows the expression vector pG31010 derived from the pET20b(+) expression vector (Novagen) and containing DNA encoding a pe1B leader peptide followed by a ubiquitin domain, factor Xa cleavage site, AHECc region and finally an affinity tag consisting of six histidine residues. A single ubiquitin domain-encoding sequence was selected by PCR from a pUC19 vector containing a sequence encoding eight ubiquitin domains (Genebank entry M26880). The DNA sequences encoding the factor Xa cleavage site and AHECc region were produced by PCR using two overlapping synthetic oligonucleotides. The DNA sequence is shown in lower case (SEQ ID NO:9) and the derived amino-acid sequence in upper case single letter code (SEQ ID NO:10). Relevant regions are marked in bold with an explanation in italics above.

[0021]FIG. 8 shows the expression vector pG31027 derived from pG31010 in which the codon for arginine 107 of pG31010 has been mutated to one for serine, thus destroying the factor Xa cleavage site. Another factor Xa cleavage site (GSGIEGRM) has then been inserted in between the codons for methionine 23 and aspartic acid 24. The DNA sequence is shown in lower case (SEQ ID NO:11) and the derived amino-acid sequence in upper case single letter code (SEQ ID NO:12). Relevant regions are marked in bold with an explanation in italics above.

[0022]FIG. 9 shows the direct binding of samples to immobilized tetanus toxoid. FIG. 9(a) shows results of ELISA analysis of samples A (protein from vectors pG31018, pG31025 and pG3010) B (protein from vectors pG31020 and pG31030) and C (protein from vectors pG31020, pG31030 and pG31027). FIG. 9b shows protein concentration required for each sample to give an optical density of 1.5 in direct ELISA.

[0023]FIG. 10 shows the inhibition of antibody binding to immobilized tetanus toxoid with free tetanus toxoid. FIG. 10(a) shows results of ELISA analysis of samples A, B and C as defined in FIG. 9. FIG. 10(b) shows binding affinity of these samples and the wild type antibody.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention relates to the use of peptides that form left-handed antiparallel α-helical coiled-coil complexes for the assembly and stabilization of antibody Fv fragment domains for their use as functional ligand-binding molecules. These peptides are referred to herein as AHEC peptides or AHEC peptide regions. Trimeric and tetrameric AHEC peptide regions can be used to stabilize and assemble proteins, protein fragments, peptides and/or other chemicals with the antibody Fv fragment and form multimeric complexes.

[0025] In one embodiment, dimeric AHEC peptide regions are used to stabilize pairs of Fv antibody fragment chains, holding the two chains together and approximately in the correct position. Antibodies are composed of two pairs of heavy and light chains. The heavy and light chains are folded into a number of domains that interact with each other giving the antibody its general form. About 100 amino-acid residues at the N-terminus of each chain vary greatly between different antibodies and form the variable or Fv domain. The Fv domains of both chains normally bind to each other to form the complementarity-determining region (CDR). Because of the variability of the two Fv domains, their binding affinity can be weak. The union and correct positioning of the two Fv domains are normally stabilized by the other antibody domains.

[0026] Because of their complex nature, requiring correct folding and disulfide linkage, functional antibodies are not easily produced recombinantly, making the expression systems required expensive and/or difficult to handle. This has to some degree been overcome by producing antibody fragments such as Fab fragments. Fab fragments contain the variable domain as well as the first constant domain of both the light and heavy chains, the constant domains being included to help stabilize the light and heavy chain complex. Fab fragments are, however, still relatively difficult to produce recombinantly. Another strategy to facilitate the production and use of recombinant antibody fragments is to express them as a single chain (scFv), where both the heavy and light chain variable regions are linked by a long linking peptide (e.g. (GGSG)₃). Linking the two Fv domains keeps them in close proximity to each other while they are dissociated. This format is often the easiest to produce recombinantly as it contains the minimum number of domains and disulfide linkages. However, it has been found that the length of linking peptide required varies from antibody to antibody. The N-termini of the Fv chains are also usually located close to if not within the CDR region and the addition or removal of the linking peptide has sometimes been found to affect binding affinity of the antibody. Other formats for stabilizing antibody fragments have also been investigated, including mutating each chain by inserting cysteine residues. These residues are then used to form a disulfide linkage between the two chains. However, because of the variability of the Fv regions, the mutation sites must be optimized for each antibody. The use of parallel helices to stabilize the antibody Fv regions helps overcome the problems of variations in the Fv domains; however, this requires the use of linking chains to span the distance between the two Fv C-termini. The unstructured nature of the linkage regions increases their susceptibility to proteolysis.

[0027] In Fab fragments or full-length antibodies the C-terminal ends of the two Fv domains are located in the order of 30-50 Å from each other.

[0028] Using AHEC peptide regions of the present invention, the antibody Fv domains can be placed at either end of the AHEC peptide region. Once bound, the AHEC peptide regions serve to stabilize the antibody Fv complex by holding the two chains in approximately the correct relative position without the need for a long linking peptide. In this embodiment, the antibody Fv domains are linked via AHEC peptides attached to their C-termini, and not the N-termini which participate in the CDR. Accordingly, their binding properties are less likely to be affected. This allows antibody Fv regions, derived from e.g. mouse IgG, to be used without incurring the risk of conformational changes in the antibody Fv complex due to the presence of an scFv linking peptide. As the Fv complex is stabilized in a manner similar to that in Fab fragments and full-length antibodies, the chance of successfully changing antibody formats is much higher. The Fv containing complex can be further stabilized by placing cysteine residues within or adjacent to the relevant AHEC peptide, thus permitting covalent linkage by the formation of an interchain disulfide bridge. The formation of interchain disulfide linkages has been demonstrated for two-stranded α-helical coiled-coils (Zhou et al. Biochemistry 1993 32:3178-3187).

[0029] As only two AHEC chains are used for Fv stabilization, the remaining peptide or peptides in trimeric and tetrameric AHEC peptide complexes can be used for the attachment of proteins, protein fragments, peptides and/ or chemicals such as functional moieties including, but not limited to, other antibodies, affinity tags, enzymatic labels, dyes, poly(ethylene glycol) (PEG), toxins and the immobilization of the AHEC complex to a solid surface (see FIG. 1). The general advantage of the invention is that it exploits the specific binding of antibodies, but instead of retaining the Fc region, with its often undesirable function of provoking inflammation and complement activation, it provides for the ready attachment of a large number of different functional groups that can be chosen to fulfill a variety of therapeutic and diagnostic applications.

[0030] The other AHEC peptide(s) in trimeric and tetrameric AHEC peptide regions can also be used to enable the Fv-AHEC complex to be displayed of on the surface of phage particles. The use of AHEC-stabilized Fv fragments in phage display allows for the selection of Fv antibody fragments that are easily produced in Escherichia coli. Such fragments can then be used, if required, in the production of full-length antibodies.

[0031] When the two AHEC chains stabilizing the Fv complex are covalently linked to each other, the other chain(s) of the AHEC complex can be readily exchanged by dissociating the AHEC complex with an agent such as 2-8 M urea and reassociating the complex in the presence of new AHEC peptide(s) linked to the new functional groups.

[0032] The formation of multimeric proteins protected by inert molecules such as PEG permits the production of modular chimeric proteins with a broad spectrum of functions and reduced immunogenicity. The AHEC region can be used to link selected proteins or protein fragments with many varied functions. For example, in one embodiment, two immunoglobulin Fv fragments can be linked to a toxin for targeted cell killing. Alternatively, an immunoglobulin fragment can be linked to an enzyme for color reactions. Both of these exemplary multimeric proteins can be produced without having to go back to the DNA level and produce new expression vectors and then express and refold the multimeric protein. The attachment of inert molecules such as PEG to the Fv-AHEC complex reduces its immunogenicity for use in therapy. Attachment of such molecules to the AHEC region is less likely to directly cause conformational changes in the Fv complex, as may happen when they are attached directly or very close to the Fv complex, as is required in scFv. Attachment of inert molecules also reduces the amount of protein exposed to proteolytic cleavage. These two factors and the increase in the size of the complex are expected to prolong the residency time of the oligomeric protein complex in the body. A decrease in the immunogenicity of the multimeric protein is an advantage when multiple treatments are required.

[0033] Accordingly, the multimeric complexes of the present invention are useful in the production of therapeutic antibodies and/or antibody fragments. The antibodies may be used for a number of functions, including the inhibition of receptor binding and the targeting of drugs, toxins and labels. The fusion or attachment of peptides constituting a trimeric AHEC region is useful in the production of humanized mouse antibodies. Further, because of the simple nature of the modified Fv complex it can be easily expressed in E. coli, thus reducing production costs. The peptides of the AHEC region can then be used for site-specific PEGylation, protecting this region both from cleavage and from recognition by the host immune system.

[0034] Peptides capable of forming an AHEC region can also be used to attach proteins to a surface. One peptide of an AHEC region can be immobilized to a surface such as a solid support directly or via a linking molecule such as PEG. This allows either covalent or non-covalent attachment of proteins to a surface without chemical treatment. This again has the advantage in that the protein is immobilized in a specific manner and is not inactivated by non-specific adsorption or by coupling reactions. Covalent or non-covalent attachment of proteins, protein fragments, peptides or chemical complexes to a surface and or solid support via an AHEC region can be performed routinely in accordance with well known procedures. Examples of surfaces or solid supports to which the complexes of the present invention may be immobilized include, but are in no way limited to, microtiter plates, slides, culture dishes and beads.

[0035] In a preferred embodiment of the present invention, peptides forming the AHEC regions are specifically designed or derived from a spectrin protein. Use of AHEC regions specifically designed or derived from a spectrin protein can improve the development of multimeric proteins for both therapeutic and diagnostic purposes. In one embodiment, non-naturally occurring multimeric proteins of the present invention are prepared using each of three α-helical coils derived from the spectrin family of proteins as separate chains (See FIG. 2b). Exemplary amino-acid sequences of the three α-helical coils derived from known spectrin repeats, namely the 16^(th) repeat of chicken brain α-spectrin (coil A is SEQ ID NO:11; coil B is SEQ ID NO:12; coil C is SEQ ID NO:13; Pascual et al. J. Mol. Biol. 1997 273:740-751) and the 14^(th) repeat of Drosophila α-spectrin (coil A is SEQ ID NO:14; coil B is SEQ ID NO:15; coil C is SEQ ID NO:16; Yan et al. Science 1993 262:2027-2030) are depicted in Table 1. TABLE 1 Amino-acid sequences of exemplary AHEC peptides derived from spectrin Coil 16^(th) repeat of chicken brain α-spectrin 14^(th) repeat of Drosophila α-spectrin A QFFRDDEESWKKLLVSSED RLQQLFRDVEDEETWIREKEPIAASTNRGK (SEQ ID NO:11) (SEQ ID NO:14) B KHKRLELAAHEPAIQGVLDTG LIKKHEDFDKAINGHEQKIAALQTVADQL (SEQ ID NO:12) (SEQ ID NO:15) C IQQRLAQFVDHWKELKQLAARG ASNLVDEKRKQVLERWRHLKEGLIEKRSRLG (SEQ ID NO:13) (SEQ ID NO:16)

[0036] In another embodiment, non-naturally occurring AHEC peptides of the present invention are prepared by de novo design. The design of AHEC peptides can also be based on the prior art for the formation of antiparallel (McClain et al. J. Am. Chem. Soc. 2001 123:3151-3152; Monera et al. J. Biol. Chem. 1993 268:19218-19227; Monera et al. Biochemistry 1994 33:3862-3871; Monera et al. J. Biol. Chem. 1996 271:3995-4001; Myszka, D. G. and Chaiken, I. M. Biochemistry 1994 33:2363-2372; Oakley, M. G. and Kim, P. S. Biochemistry 1998 37:12603-12610), dimeric (McClain et al. J. Am. Chem. Soc. 2001 123:3151-3152; Monera et al. J. Biol. Chem. 1993 268:19218-19227; Monera et al. Biochemistry 1994 33:3862-3871; Monera et al. J. Biol. Chem. 1996 271:3995-4001; Myszka, D. G. and Chaiken, I. M. Biochemistry 1994 33:2363-2372) and tetrameric (Betz et al. Biochemistry 1997 36:2450-2458; Harbury et al. Science 1993 262:1401-1407; Monera Protein Eng. 1996 9:353-363) coiled coils, examples of each being given in Table 2. TABLE 2 Amino-acid sequences of exemplary de novo designed AHEC peptides Coil Dimeric Trimeric tetrameric A QALEKELAQNEWELQALEKELAQLEKELQA AIEYEQAAIKEEIAAIKDKIAAIKEYIA SAQRLLKIARRLRKEAKELLKRAEHG (SEQ ID NO:17) (SEQ ID NO:19) (SEQ ID NO:22) B QALKKKLLAQLKWKLQALKKKNAQLKKKLQA AILYKIAAIEEKIAQIEEEIAAQEEKIA GPELLKKVEELEKKVDKLYKIVEHG (SEQ ID NO:18) (SEQ ID NO:20) (SEQ ID NO:23) C AIKYKQAAIKNEIAAIKQEIAAIEQMIA SAQELLKIARRLRKEAKELLKEAEHG (SEQ ID NQ:21) (SEQ ID NO:24) D GPRLLKEVEELEKKVDELYKIVEHG (SEQ ID NO:25)

[0037] The following non-limiting examples are provided to further illustrate the present invention.

EXAMPLES Example 1 AHEC Peptides and Fv Fragments

[0038] AHEC peptides were selected form human spectrin (Genebank entry U83867; SEQ ID NO:26), AHECa consisting of residues 783-811, AHECb residues 825-853, and AHECc residues 858-885. The Fv sequences are derived from the mouse monoclonal anti-tetanus toxoid antibody HYB 278-14.

Example 2 Expression Vector Construction

[0039] The pG31018 expression vector (FIG. 3) was derived from a pET20b(+) expression vector (Novagene) and contained DNA encoding the light-chain Fv domain of antibody HYB 278-14 followed by an AHECa region and finally by an affinity tag of six histidine residues.

[0040] The pG31020 expression vector (FIG. 4) was derived from pG31018 by mutating the codon for valine 122 to one for cysteine.

[0041] The pG31025 expression vector (FIG. 5) was derived from a pET20b(+) expression vector (Novagene) and contained DNA encoding a pe1B leader peptide followed by a factor Xa cleavage site, the heavy-chain Fv domain of antibody HYB 278-14, an AHECb region and finally an affinity tag of six histidine residues.

[0042] The pG31030 expression vector (FIG. 6) was derived from pG31025 by mutating the codon for valine 176 to one for cysteine.

[0043] The pG31010 expression vector (FIG. 7) was derived from the pET20b(+) expression vector (Novagen) and consisted of DNA encoding a N-terminal pe1B leader peptide followed by a ubiquitin domain, factor Xa cleavage site, an AHECc region, and finally an affinity tag of six histidine residues. A single ubiquitin domain encoding sequence was selected by means of PCR from a pUC19 vector containing a sequence encoding eight ubiquitin domains (Genebank entry M26880). The DNA sequences encoding the factor Xa cleavage site and the AHECc region were produced by PCR using two overlapping synthetic oligonucleotides.

[0044] The pG31027 expression vector (FIG. 8) was derived from pG31010. Arginine 107 of pG31010 was mutated to a serine, thus destroying the factor Xa cleavage site. Another factor Xa cleavage site (GSGIEGRM (SEQ ID NO:27)) was then inserted between methionine 23 and aspartic acid 24.

Example 3 Protein Expression

[0045] FvL-AHECa Constructs

[0046] The expression vectors pG31018 and pG31020 were transformed into BL21(DE3) (Stratagene) E. coli by means of a standard heat-shock method. Transformed cells were selected on LB agar plates containing 100 mM ampicillin. Cultures were grown overnight at 30° C., with mixing, in 25 mL LB medium containing 100 mM ampicillin. The overnight culture was then transferred to 1 liter LB medium containing 100 mM ampicillin and incubated at 37° C. with mixing until the optical density at 600 nm of the medium was about 0.6. Expression was induced by the addition of isopropyl β-D-1-thiogalactopyranoside to a final concentration of 1 mM. Induction was carried out for three hours. The cells were harvested by centrifugation at 5000 rpm for 10 minutes at 4° C. The cell pellet was resuspended on ice in 50 ml 8 M urea, containing 500 mM NaCl, 20 mM phosphate buffer and 5 mM β-mercaptoethanol, pH 7.4. The E. coli cells were lyzed by freezing and thawing followed by sonication on ice for 5×20 seconds with a 20-second pause between cycles. Particulate matter was removed by centrifugation at 15,000 g for 20 minutes at 4° C. The supernatant was then filtered through a 0.45 μm pore-size filter ready for Ni-column purification.

[0047] FvH-AHECb Constructs

[0048] The expression vectors pG31025 and pG31030 were transformed into BL21 E. coli (Stratagene) by means of a standard heat-shock method. Transformed cells were selected on LB agar plates containing 100 mM ampicillin. Cultures were grown overnight at 30° C., with mixing, in 25 mL LB medium containing 100 mM ampicillin. The overnight culture was then transferred to 1 liter LB medium containing 100 mM ampicillin and incubated at 37° C. with mixing, until the optical density at 600 nm of the medium was about 0.6. Expression was induced by the introduction of λCE6 phage to a final concentration of 4×10⁹ pfu/ml. Induction was carried out for three hours. The cells were harvested by centrifugation at 5000 rpm for 10 minutes at 4° C. The cell pellet was resuspended on ice in 50 ml 8 M urea containing 500 mM NaCl, 20 mM phosphate buffer and 5 mM β-mercaptoethanol, pH 7.4. The E. coli were lyzed by freezing and thawing followed by sonication on ice for 5×20 seconds with a 20-second pause between cycles. Particulate matter was removed by centrifugation at 15,000 g for 20 minutes at 4° C. The supernatant was then filtered through a 0.45 μm pore-size filter ready for Ni-column purification.

[0049] Ubiquitin-AHECc Constructs

[0050] The expression vectors pG31010 and pG31027 were transformed into BL21(DE3) (Stratagene) and NovoBlue(DE3) (Novagen) E. coli, respectively, by means of a standard heat-shock method. Transformed cells were selected on LB agar plates containing 100 mM ampicillin. Cultures were grown overnight at 30° C., with mixing, in 25 mL LB medium containing 100 mM ampicillin. The overnight culture was then transferred to 1 liter LB medium containing 100 mM ampicillin and incubated at 37° C. with mixing, until the optical density at 600 nm of the medium was about 0.6. Expression was induced by the addition of isopropyl β-D-1-thiogalactopyranoside to a final concentration of 1 mM. Induction was carried out for three hours. The cells were harvested by centrifugation at 5000 rpm for 10 minutes at 4° C. The cell pellet was resuspended on ice in 50 ml 8 M urea containing 500 mM NaCl, 20 mM phosphate buffer and 5 mM β-mercaptoethanol, pH 7.4. The E. coli were lyzed by freezing and thawing followed by sonication on ice for 5×20 seconds with a 20-second pause between cycles. Particulate matter was removed by centrifugation at 15,000 g for 20 minutes at 4° C. The supernatant was then filtered through a 0.45 μm pore-size filter ready for Ni-column purification.

Example 4 Protein Purification

[0051] The affinity tag consisting of six histidine residues was used to purify all protein constructs on a prepacked 5-ml Ni²⁺ chelating (Ni-ETA) column (Pharmacia). All liquid chromatography was carried out on an ÄKTA prime system (Pharmacia). The Ni-ETA column was first washed with 10-20 ml wash buffer (20 mM phosphate buffer, pH 7.4, containing 8 M urea, 500 mM NaCl, 20 mM EDTA and 5.0 mM β-mercaptoethanol) followed by 20 ml eluting buffer (20 mM phosphate buffer, pH 7.4, containing 8 M urea, 500 mM NaCl, 300 mM imidazole and 5.0 mM β-mercaptoethanol). The column was then loaded with 5 ml 10 mM NiCl₂ and washed with another 25 ml eluting buffer. The Ni-ETA column was then equilibrated with 20 ml loading buffer (20 mM phosphate buffer, pH 7.4, containing 8 M urea, 500 mM NaCl, 1 mM imidazole and 0.5 mM β-mercaptoethanol). The expression extract (Example 2) was then loaded onto the column at a flow rate of 2.0 mL per minute and washed with the loading buffer until a stable optical density baseline was achieved. At this point the column was eluted with an 80-ml buffer gradient to 100% eluting buffer, 8-ml fractions being collected. All the constructs emerged from the column as broad peaks with a maximum at around 66% elution buffer. Fractions containing this peak were then pooled for analysis.

[0052] The protein concentration of each construct was estimated by measuring the optical density at 280 nm. The theoretical extinction coefficient for each construct was determined from its amino-acid sequence according to Gill and von Hippel (Anal. Biochem. 1989 182:319). The calculated values are given in Table 3. TABLE 3 Summary of parameters calculated for each antibody fragment construct. Protein Expression Molecular weight E_(280 nm) 0.1% containing vector (Da) (= 1 g/l) FvL pG31018 18614.6 1.099 pG31020 18618.6 1.099 FvH pG31025 21678.5 1.764 pG31030 21682.5 1.764 Ubiquitin pG31010 16815.3 0.491 pG31027 17534.1 0.471

Example 5 Protein Folding and Factor Xa Treatment

[0053] In the current example three separate combinations of the purified protein were examined: (A) Protein from vectors pG31018, pG31025 and pG31010; (B) Protein from vectors pG31020 and pG31030; (C) Protein from vectors pG31020, pG31030 and pG31027.

[0054] For each folding, equal amounts of the purified constructs were combined in a 3.5 kDa cutoff dialysis tube and placed in 250 ml buffer A (8 M urea, 500 mM NaCl, 50 mM Tris-HCl, pH 8.0, 5 mM EDTA, 2 mM glutathione). This was allowed to equilibrate for 2-4 hours before folding was commenced. 1 liter of buffer B (500 mM NaCl, 50 mM Tris-HCl, pH 8.0, 5 mM EDTA, 2/0.2 mM reduced/oxidized glutathione) was then steadily added to buffer B with mixing over 24 hours. The total buffer volume was kept at 250 ml. On completion of the process, the folding mixture was dialyzed into 150 mM NaCl, 50 mM Tris-HCl, pH 8.0. The mixture was then centrifuged at 15,000 g for 20 minutes and then filtered through a 0.80-μm pore-sized filter. An extinction coefficient averaged between each component in the folding mixture was used to estimate the protein concentration. Factor Xa was added to the samples to a mass ratio of 1:50 to the estimated protein in the sample. This was then allowed to react overnight at 4° C.

Example 6 Analysis by Direct Binding ELISA

[0055] The three folded protein samples (A, B and C) were analyzed for direct binding to tetanus toxoid. MaxiSorp microtiter plates (Nunc) were coated overnight at 4° C. with 100 μl/well of 2 μg/ml tetanus toxoid in phosphate-buffered saline (PBS). The plates were washed 3×3 minutes with wash buffer (10 mM phosphate buffer, pH 7.2, containing 0.5 M NaCl and 0.1% v/v Triton X-100). The samples were diluted to a total protein concentration of 256 μg/ml in dilution buffer (wash buffer containing 1.0% w/v bovine serum albumin. Four-fold serial dilutions of the samples were prepared and added to the wells at 100 μl/well. The plate was then incubated for one hour at room temperature before washing as previously described. Bound antibody fragments were detected by means of a horseradish peroxidase-labeled anti-His-tag antibody (R931-25, Invitrogen) diluted 1/4000 in dilution buffer. The plate was incubated for a further hour and then washed as previously described. The plate was then developed with substrate solution containing 0.4 mg/ml ortho-phenylenediamine (OPD) and 0.4 μl/ml 35% hydrogen peroxide in 65 mM phosphate/35 mM citrate buffer, pH 5.0.

Example 7 Analysis By Inhibition ELISA

[0056] Known amounts of tetanus toxoid and or diphtheria toxoid (10-0 μg/ml) in dilution buffer were then incubated with the construct samples (A and B 64 μg/ml, C 16 μg/ml) overnight at 4° C. Samples of 100 μl of the incubates were then transferred to MaxiSorp microtiter plates (Nunc) coated with tetanus toxoid as previously described. Plates were incubated for one hour, washed and bound antibody fragments were detected by means of horseradish peroxidase-labeled anti-His-tag antibody (R931-25, Invitrogen) diluted 1/4000 in dilution buffer. The plate was incubated for a further hour, washed and developed with substrate solution as described above.

Example 8 Binding Properties of Construct Combinations

[0057] The six constructs summarized in Table 3 were expressed and purified as described. The molecular weight and purity was examined by mass spectroscopy and SDS-PAGE. Three separate combinations of the constructs were produced: A) pG31018, pG31025 and pG31010, consisting of FvL-AHECa; FvH-AHECb and AHECc without disulfide linkage; B) pG31020 and pG31030, consisting of FvL-AHECa and FvH-AHECb stabilized by a disulfide bridge; C) pG31020, pG31030 and pG31027, consisting of FvL-AHECa; FvH-AHECb and ubiquitin-AHECc with a disulfide bridge between AHECa and AHECb. The direct binding of these samples to tetanus toxoid is shown in FIG. 9. The concentrations required to give optical density values of 1.5 values (FIG. 9b) relate to both the relative concentration and affinity of functional antigen binding sites (FBS) in the samples. The ability of the construct combinations to bind specifically to tetanus toxoid was examined in an inhibition assay in which the sample was first incubated with a serial dilution of free tetanus toxoid. Then the amount of binding to immobilized tetanus toxoid was determined (FIG. 10a). This showed that all construct combinations bound specifically to tetanus toxoid. Binding of both samples B and C to the tetanus toxoid coat could be totally inhibited with free tetanus toxoid, whereas 20% of the binding of sample A could not be inhibited with free tetanus toxoid, indicating that sample A showed some non-specific interaction. Values for the affinity constants of the construct combinations and the parent antibody were determined from the inhibition assay and are shown in FIG. 10b. Samples B and C have similar affinities for tetanus toxoid, whereas sample A shows a four-fold lower affinity. This is likely to be due to the dissociation of the FvL and FvH complex disturbing the FBS. The formation of a disulfide linkage between AHECa and AHECb in samples B and C covalently attaches the FvL and FvH chains, reducing dissociation of the FBS. As stated earlier the lower affinity of the antibody construct of sample A will also affect the total concentration at which it gives an optical density of 1.5 on direct binding. Because of the lower affinity, more FBS in sample A is needed to achieve the same direct binding. Calculating the relative amounts of FBS in samples A, B and C from the data of FIGS. 9b and 10 b shows that sample A contains about half as much FBS (53%) as sample C, and that sample B, lacking AHECc, contains about 6% of the amount of FBS in sample C. This shows that FBS formation occurs more readily when all three AHEC chains are present and that disulfide bridging stabilizes the FBS.

[0058] In summary, these results show that sample C, which contains all three AHEC components and is disulfide linked, is able to form more FBS with a higher affinity than the other two samples. Comparison of samples B and C also shows that once the construct combination is disulfide-stabilized, the affinity achieved is not greatly affected by the presence or absence of the third AHEC member (AHECc).

1 29 1 543 DNA Artificial sequence Synthetic 1 catatggaca tcgtgatgac ccagtctcaa aaattcatgt ccacatcagt aggagacagg 60 gtcagcgtca cctgcaaggc cagtcagaat gtgggtgcta gtgtagcctg gtatcaacag 120 aaaccaggac aatctcctaa aatactgatt tactcggcat cctaccggta cagtggagtc 180 cctgatcgct tcacaggcag tggatctggg acagatttca ctctcaccat cagcaatgtg 240 cagtctgaag acttggcaga gtatttctgt cagcaatata acggctatcc tctcacgttc 300 ggtgctggga ccaagctgga gctgagaact agtgattctc tgcggttgca gcagctcttc 360 cgggatgttg aggatgagga gacgtggatt cgagagaaag agcccattgc cgcatctacc 420 gccatggata tcggaattaa ttcggatccg aattcgagct ccgtcgacaa gcttgcggcc 480 gcactcgagc accaccacca ccaccactga gatccggctg ctaacaaagc ccgaaaggaa 540 gct 543 2 168 PRT Artificial sequence Synthetic 2 Met Asp Ile Val Met Thr Gln Ser Gln Lys Phe Met Ser Thr Ser Val 1 5 10 15 Gly Asp Arg Val Ser Val Thr Cys Lys Ala Ser Gln Asn Val Gly Ala 20 25 30 Ser Val Ala Trp Tyr Gln Gln Lys Pro Gly Gln Ser Pro Lys Ile Leu 35 40 45 Ile Tyr Ser Ala Ser Tyr Arg Tyr Ser Gly Val Pro Asp Arg Phe Thr 50 55 60 Gly Ser Gly Ser Gly Thr Asp Phe Thr Leu Thr Ile Ser Asn Val Gln 65 70 75 80 Ser Glu Asp Leu Ala Glu Tyr Phe Cys Gln Gln Tyr Asn Gly Tyr Pro 85 90 95 Leu Thr Phe Gly Ala Gly Thr Lys Leu Glu Leu Arg Thr Ser Asp Ser 100 105 110 Leu Arg Leu Gln Gln Leu Phe Arg Asp Val Glu Asp Glu Glu Thr Trp 115 120 125 Ile Arg Glu Lys Glu Pro Ile Ala Ala Ser Thr Ala Met Asp Ile Gly 130 135 140 Ile Asn Ser Asp Pro Asn Ser Ser Ser Val Asp Lys Leu Ala Ala Ala 145 150 155 160 Leu Glu His His His His His His 165 3 543 DNA Artificial sequence Synthetic 3 catatggaca tcgtgatgac ccagtctcaa aaattcatgt ccacatcagt aggagacagg 60 gtcagcgtca cctgcaaggc cagtcagaat gtgggtgcta gtgtagcctg gtatcaacag 120 aaaccaggac aatctcctaa aatactgatt tactcggcat cctaccggta cagtggagtc 180 cctgatcgct tcacaggcag tggatctggg acagatttca ctctcaccat cagcaatgtg 240 cagtctgaag acttggcaga gtatttctgt cagcaatata acggctatcc tctcacgttc 300 ggtgctggga ccaagctgga gctgagaact agtgattctc tgcggttgca gcagctcttc 360 cgggattgtg aggatgagga gacgtggatt cgagagaaag agcccattgc cgcatctacc 420 gccatggata tcggaattaa ttcggatccg aattcgagct ccgtcgacaa gcttgcggcc 480 gcactcgagc accaccacca ccaccactga gatccggctg ctaacaaagc ccgaaaggaa 540 gct 543 4 168 PRT Artificial sequence Synthetic 4 Met Asp Ile Val Met Thr Gln Ser Gln Lys Phe Met Ser Thr Ser Val 1 5 10 15 Gly Asp Arg Val Ser Val Thr Cys Lys Ala Ser Gln Asn Val Gly Ala 20 25 30 Ser Val Ala Trp Tyr Gln Gln Lys Pro Gly Gln Ser Pro Lys Ile Leu 35 40 45 Ile Tyr Ser Ala Ser Tyr Arg Tyr Ser Gly Val Pro Asp Arg Phe Thr 50 55 60 Gly Ser Gly Ser Gly Thr Asp Phe Thr Leu Thr Ile Ser Asn Val Gln 65 70 75 80 Ser Glu Asp Leu Ala Glu Tyr Phe Cys Gln Gln Tyr Asn Gly Tyr Pro 85 90 95 Leu Thr Phe Gly Ala Gly Thr Lys Leu Glu Leu Arg Thr Ser Asp Ser 100 105 110 Leu Arg Leu Gln Gln Leu Phe Arg Asp Cys Glu Asp Glu Glu Thr Trp 115 120 125 Ile Arg Glu Lys Glu Pro Ile Ala Ala Ser Thr Ala Met Asp Ile Gly 130 135 140 Ile Asn Ser Asp Pro Asn Ser Ser Ser Val Asp Lys Leu Ala Ala Ala 145 150 155 160 Leu Glu His His His His His His 165 5 615 DNA Artificial sequence Synthetic 5 atgaaatacc tgctgccgac cgctgctgct ggtctgctgc tcctcgctgc ccagccggcg 60 atggccatgg gtagcggaat cgaagggcgc atggcgtctg aggtccagct gcagcagtct 120 ggacctgaac tggtaaagcc tggggcttca gtgaagatgt cctgcaaggc ttctggatac 180 acattcacta actatattat gtattgggtg acgcagaggc ctgggcaggg ccttgagtgg 240 attggatata ttcatcctta caatgatgat actaaataca atgagaagtt caaagacaag 300 gccacactga cttcagacag atcctcccgc acagcctaca tggagctcag cagcctgacc 360 tctgaggact ctgcggtcta ttactgtgca aggaagaagg ctaactttgg ttacggcccc 420 tggtttgctt actggggcca agggactctg gtcactgtct ctgcacgtac gaaacatcaa 480 gccttacaag cagaaattgc tggacatgaa ccacgcatca aagcagttac acagaagggg 540 aatgcgatgg tggaggaatc actcgagcac caccaccacc accactgaga tccggctgct 600 aacaaagccc gaaag 615 6 195 PRT Artificial sequence Synthetic 6 Met Lys Tyr Leu Leu Pro Thr Ala Ala Ala Gly Leu Leu Leu Leu Ala 1 5 10 15 Ala Gln Pro Ala Met Ala Met Gly Ser Gly Ile Glu Gly Arg Met Ala 20 25 30 Ser Glu Val Gln Leu Gln Gln Ser Gly Pro Glu Leu Val Lys Pro Gly 35 40 45 Ala Ser Val Lys Met Ser Cys Lys Ala Ser Gly Tyr Thr Phe Thr Asn 50 55 60 Tyr Ile Met Tyr Trp Val Thr Gln Arg Pro Gly Gln Gly Leu Glu Trp 65 70 75 80 Ile Gly Tyr Ile His Pro Tyr Asn Asp Asp Thr Lys Tyr Asn Glu Lys 85 90 95 Phe Lys Asp Lys Ala Thr Leu Thr Ser Asp Arg Ser Ser Arg Thr Ala 100 105 110 Tyr Met Glu Leu Ser Ser Leu Thr Ser Glu Asp Ser Ala Val Tyr Tyr 115 120 125 Cys Ala Arg Lys Lys Ala Asn Phe Gly Tyr Gly Pro Trp Phe Ala Tyr 130 135 140 Trp Gly Gln Gly Thr Leu Val Thr Val Ser Ala Arg Thr Lys His Gln 145 150 155 160 Ala Leu Gln Ala Glu Ile Ala Gly His Glu Pro Arg Ile Lys Ala Val 165 170 175 Thr Gln Lys Gly Asn Ala Met Val Glu Glu Ser Leu Glu His His His 180 185 190 His His His 195 7 615 PRT Artificial sequence Synthetic 7 Ala Thr Gly Ala Ala Ala Thr Ala Cys Cys Thr Gly Cys Thr Gly Cys 1 5 10 15 Cys Gly Ala Cys Cys Gly Cys Thr Gly Cys Thr Gly Cys Thr Gly Gly 20 25 30 Thr Cys Thr Gly Cys Thr Gly Cys Thr Cys Cys Thr Cys Gly Cys Thr 35 40 45 Gly Cys Cys Cys Ala Gly Cys Cys Gly Gly Cys Gly Ala Thr Gly Gly 50 55 60 Cys Cys Ala Thr Gly Gly Gly Thr Ala Gly Cys Gly Gly Ala Ala Thr 65 70 75 80 Cys Gly Ala Ala Gly Gly Gly Cys Gly Cys Ala Thr Gly Gly Cys Gly 85 90 95 Thr Cys Thr Gly Ala Gly Gly Thr Cys Cys Ala Gly Cys Thr Gly Cys 100 105 110 Ala Gly Cys Ala Gly Thr Cys Thr Gly Gly Ala Cys Cys Thr Gly Ala 115 120 125 Ala Cys Thr Gly Gly Thr Ala Ala Ala Gly Cys Cys Thr Gly Gly Gly 130 135 140 Gly Cys Thr Thr Cys Ala Gly Thr Gly Ala Ala Gly Ala Thr Gly Thr 145 150 155 160 Cys Cys Thr Gly Cys Ala Ala Gly Gly Cys Thr Thr Cys Thr Gly Gly 165 170 175 Ala Thr Ala Cys Ala Cys Ala Thr Thr Cys Ala Cys Thr Ala Ala Cys 180 185 190 Thr Ala Thr Ala Thr Thr Ala Thr Gly Thr Ala Thr Thr Gly Gly Gly 195 200 205 Thr Gly Ala Cys Gly Cys Ala Gly Ala Gly Gly Cys Cys Thr Gly Gly 210 215 220 Gly Cys Ala Gly Gly Gly Cys Cys Thr Thr Gly Ala Gly Thr Gly Gly 225 230 235 240 Ala Thr Thr Gly Gly Ala Thr Ala Thr Ala Thr Thr Cys Ala Thr Cys 245 250 255 Cys Thr Thr Ala Cys Ala Ala Thr Gly Ala Thr Gly Ala Thr Ala Cys 260 265 270 Thr Ala Ala Ala Thr Ala Cys Ala Ala Thr Gly Ala Gly Ala Ala Gly 275 280 285 Thr Thr Cys Ala Ala Ala Gly Ala Cys Ala Ala Gly Gly Cys Cys Ala 290 295 300 Cys Ala Cys Thr Gly Ala Cys Thr Thr Cys Ala Gly Ala Cys Ala Gly 305 310 315 320 Ala Thr Cys Cys Thr Cys Cys Cys Gly Cys Ala Cys Ala Gly Cys Cys 325 330 335 Thr Ala Cys Ala Thr Gly Gly Ala Gly Cys Thr Cys Ala Gly Cys Ala 340 345 350 Gly Cys Cys Thr Gly Ala Cys Cys Thr Cys Thr Gly Ala Gly Gly Ala 355 360 365 Cys Thr Cys Thr Gly Cys Gly Gly Thr Cys Thr Ala Thr Thr Ala Cys 370 375 380 Thr Gly Thr Gly Cys Ala Ala Gly Gly Ala Ala Gly Ala Ala Gly Gly 385 390 395 400 Cys Thr Ala Ala Cys Thr Thr Thr Gly Gly Thr Thr Ala Cys Gly Gly 405 410 415 Cys Cys Cys Cys Thr Gly Gly Thr Thr Thr Gly Cys Thr Thr Ala Cys 420 425 430 Thr Gly Gly Gly Gly Cys Cys Ala Ala Gly Gly Gly Ala Cys Thr Cys 435 440 445 Thr Gly Gly Thr Cys Ala Cys Thr Gly Thr Cys Thr Cys Thr Gly Cys 450 455 460 Ala Cys Gly Thr Ala Cys Gly Ala Ala Ala Cys Ala Thr Cys Ala Ala 465 470 475 480 Gly Cys Cys Thr Thr Ala Cys Ala Ala Gly Cys Ala Gly Ala Ala Ala 485 490 495 Thr Thr Gly Cys Thr Gly Gly Ala Cys Ala Thr Gly Ala Ala Cys Cys 500 505 510 Ala Cys Gly Cys Ala Thr Cys Ala Ala Ala Gly Cys Ala Thr Gly Thr 515 520 525 Ala Cys Ala Cys Ala Gly Ala Ala Gly Gly Gly Gly Ala Ala Thr Gly 530 535 540 Cys Gly Ala Thr Gly Gly Thr Gly Gly Ala Gly Gly Ala Ala Thr Cys 545 550 555 560 Ala Cys Thr Cys Gly Ala Gly Cys Ala Cys Cys Ala Cys Cys Ala Cys 565 570 575 Cys Ala Cys Cys Ala Cys Cys Ala Cys Thr Gly Ala Gly Ala Thr Cys 580 585 590 Cys Gly Gly Cys Thr Gly Cys Thr Ala Ala Cys Ala Ala Ala Gly Cys 595 600 605 Cys Cys Gly Ala Ala Ala Gly 610 615 8 195 PRT Artificial sequence Synthetic 8 Met Lys Tyr Leu Leu Pro Thr Ala Ala Ala Gly Leu Leu Leu Leu Ala 1 5 10 15 Ala Gln Pro Ala Met Ala Met Gly Ser Gly Ile Glu Gly Arg Met Ala 20 25 30 Ser Glu Val Gln Leu Gln Gln Ser Gly Pro Glu Leu Val Lys Pro Gly 35 40 45 Ala Ser Val Lys Met Ser Cys Lys Ala Ser Gly Tyr Thr Phe Thr Asn 50 55 60 Tyr Ile Met Tyr Trp Val Thr Gln Arg Pro Gly Gln Gly Leu Glu Trp 65 70 75 80 Ile Gly Tyr Ile His Pro Tyr Asn Asp Asp Thr Lys Tyr Asn Glu Lys 85 90 95 Phe Lys Asp Lys Ala Thr Leu Thr Ser Asp Arg Ser Ser Arg Thr Ala 100 105 110 Tyr Met Glu Leu Ser Ser Leu Thr Ser Glu Asp Ser Ala Val Tyr Tyr 115 120 125 Cys Ala Arg Lys Lys Ala Asn Phe Gly Tyr Gly Pro Trp Phe Ala Tyr 130 135 140 Trp Gly Gln Gly Thr Leu Val Thr Val Ser Ala Arg Thr Lys His Gln 145 150 155 160 Ala Leu Gln Ala Glu Ile Ala Gly His Glu Pro Arg Ile Lys Ala Cys 165 170 175 Thr Gln Lys Gly Asn Ala Met Val Glu Glu Ser Leu Glu His His His 180 185 190 His His His 195 9 480 DNA Artificial sequence Synthetic 9 atgaaatacc tgctgccgac cgctgctgct ggtctgctgc tcctcgctgc ccagccggcg 60 atggccatgg atatcatgca gatcttcgtg aagactctga ctggtaagac catcaccctc 120 gaggtggagc ccagtgacac catcgagaat gtcaaggcaa agatccaaga taaggaaggc 180 attcctcctg atcagcagag gttgatcttt gccggaaaac agctggaaga tggtcgtacc 240 ctgtctgact acaacatcca gaaagagtcc accttgcacc tggtactccg tctcagagga 300 ggaggatcca tagaaggtcg tggatctgag gatgtgaagg ccaagcttca cgagctgaac 360 caaaagtggg aggcactgaa agccaaagct tcccagcgtc ggcaggacgt cgacaagctt 420 gcggccgcac tcgagcacca ccaccaccac cactgagatc cggctgctaa caaagcccga 480 10 151 PRT Artificial sequence Synthetic 10 Met Lys Tyr Leu Leu Pro Thr Ala Ala Ala Gly Leu Leu Leu Leu Ala 1 5 10 15 Ala Gln Pro Ala Met Ala Met Asp Ile Met Gln Ile Phe Val Lys Thr 20 25 30 Leu Thr Gly Lys Thr Ile Thr Leu Glu Val Glu Pro Ser Asp Thr Ile 35 40 45 Glu Asn Val Lys Ala Lys Ile Gln Asp Lys Glu Gly Ile Pro Pro Asp 50 55 60 Gln Gln Arg Leu Ile Phe Ala Gly Lys Gln Leu Glu Asp Gly Arg Thr 65 70 75 80 Leu Ser Asp Tyr Asn Ile Gln Lys Glu Ser Thr Leu His Leu Val Leu 85 90 95 Arg Leu Arg Gly Gly Gly Ser Ile Glu Gly Arg Gly Ser Glu Asp Val 100 105 110 Lys Ala Lys Leu His Glu Leu Asn Gln Lys Trp Glu Ala Leu Lys Ala 115 120 125 Lys Ala Ser Gln Arg Arg Gln Asp Val Asp Lys Leu Ala Ala Ala Leu 130 135 140 Glu His His His His His His 145 150 11 504 DNA Artificial sequence Synthetic 11 atgaaatacc tgctgccgac cgctgctgct ggtctgctgc tcctcgctgc ccagccggcg 60 atggccatgg gtagcggaat cgaagggcgc atggatatca tgcaaatctt cgtgaagact 120 ctgactggta agaccatcac cctcgaggtg gagcccagtg acaccatcga gaatgtcaag 180 gcaaagatcc aagataagga aggcattcct cctgatcagc agaggttgat ctttgccgga 240 aaacagctgg aagatggtcg taccctgtct gactacaaca tccagaaaga gtccaccttg 300 cacctggtac tccgtctcag aggaggagga tccatagaag gtagtggatc tgaggatgtg 360 aaggccaagc ttcacgagct gaaccaaaag tgggaggcac tgaaagccaa agcttcccag 420 cgtcggcagg acgtcgacaa gcttgcggcc gcactcgagc accaccacca ccaccactga 480 gatccggctg ctaacaaagc ccga 504 12 159 PRT Artificial sequence Synthetic 12 Met Lys Tyr Leu Leu Pro Thr Ala Ala Ala Gly Leu Leu Leu Leu Ala 1 5 10 15 Ala Gln Pro Ala Met Ala Met Gly Ser Gly Ile Glu Gly Arg Met Asp 20 25 30 Ile Met Gln Ile Phe Val Lys Thr Ile Lys Thr Leu Thr Gly Thr Leu 35 40 45 Glu Val Glu Pro Ser Asp Thr Ile Glu Asn Val Lys Ala Lys Ile Gln 50 55 60 Asp Lys Glu Gly Ile Pro Pro Asp Gln Gln Arg Leu Ile Phe Ala Gly 65 70 75 80 Lys Gln Leu Glu Asp Gly Arg Thr Leu Ser Asp Tyr Asn Ile Gln Lys 85 90 95 Glu Ser Thr Leu His Leu Val Leu Arg Leu Arg Gly Gly Gly Ser Ile 100 105 110 Glu Gly Ser Gly Ser Glu Asp Val Lys Ala Lys Leu His Glu Leu Asn 115 120 125 Gln Lys Trp Glu Ala Leu Lys Ala Lys Ala Ser Gln Arg Arg Gln Asp 130 135 140 Val Asp Lys Leu Ala Ala Ala Leu Glu His His His His His His 145 150 155 13 19 PRT Gallus sp. 13 Gln Phe Phe Arg Asp Asp Glu Glu Ser Trp Lys Lys Leu Leu Val Ser 1 5 10 15 Ser Glu Asp 14 21 PRT Gallus sp. 14 Lys His Lys Arg Leu Glu Leu Ala Ala His Glu Pro Ala Ile Gln Gly 1 5 10 15 Val Leu Asp Thr Gly 20 15 22 PRT Gallus sp. 15 Ile Gln Gln Arg Leu Ala Gln Phe Val Asp His Trp Lys Glu Leu Lys 1 5 10 15 Gln Leu Ala Ala Arg Gly 20 16 30 PRT Drosophila sp. 16 Arg Leu Gln Gln Leu Phe Arg Asp Val Glu Asp Glu Glu Thr Trp Ile 1 5 10 15 Arg Glu Lys Glu Pro Ile Ala Ala Ser Thr Asn Arg Gly Lys 20 25 30 17 29 PRT Drosophila sp. 17 Leu Ile Lys Lys His Glu Asp Phe Asp Lys Ala Ile Asn Gly His Glu 1 5 10 15 Gln Lys Ile Ala Ala Leu Gln Thr Val Ala Asp Gln Leu 20 25 18 31 PRT Drosophila sp. 18 Ala Ser Asn Leu Val Asp Glu Lys Arg Lys Gln Val Leu Glu Arg Trp 1 5 10 15 Arg His Leu Lys Glu Gly Leu Ile Glu Lys Arg Ser Arg Leu Gly 20 25 30 19 30 PRT Artificial sequence Synthetic 19 Gln Ala Leu Glu Lys Glu Leu Ala Gln Asn Glu Trp Glu Leu Gln Ala 1 5 10 15 Leu Glu Lys Glu Leu Ala Gln Leu Glu Lys Glu Leu Gln Ala 20 25 30 20 31 PRT Artificial sequence Synthetic 20 Gln Ala Leu Lys Lys Lys Leu Leu Ala Gln Leu Lys Trp Lys Leu Gln 1 5 10 15 Ala Leu Lys Lys Lys Asn Ala Gln Leu Lys Lys Lys Leu Gln Ala 20 25 30 21 28 PRT Artificial sequence Synthetic 21 Ala Ile Glu Tyr Glu Gln Ala Ala Ile Lys Glu Glu Ile Ala Ala Ile 1 5 10 15 Lys Asp Lys Ile Ala Ala Ile Lys Glu Tyr Ile Ala 20 25 22 28 PRT Artificial sequence Synthetic 22 Ala Ile Leu Tyr Lys Ile Ala Ala Ile Glu Glu Lys Ile Ala Gln Ile 1 5 10 15 Glu Glu Glu Ile Ala Ala Gln Glu Glu Lys Ile Ala 20 25 23 28 PRT Artificial sequence Synthetic 23 Ala Ile Lys Tyr Lys Gln Ala Ala Ile Lys Asn Glu Ile Ala Ala Ile 1 5 10 15 Lys Gln Glu Ile Ala Ala Ile Glu Gln Met Ile Ala 20 25 24 24 PRT Artificial sequence Synthetic 24 Ser Ala Gln Arg Leu Leu Lys Ile Ala Arg Arg Leu Arg Lys Glu Ala 1 5 10 15 Lys Glu Leu Leu Lys Arg Ala Glu 20 25 25 PRT Artificial sequence Synthetic 25 Gly Pro Glu Leu Leu Lys Lys Val Glu Glu Leu Glu Lys Lys Val Asp 1 5 10 15 Lys Leu Tyr Lys Ile Val Glu His Gly 20 25 26 26 PRT Artificial sequence Synthetic 26 Ser Ala Gln Glu Leu Leu Lys Ile Ala Arg Arg Leu Arg Lys Glu Ala 1 5 10 15 Lys Glu Leu Leu Lys Glu Ala Glu His Gly 20 25 27 25 PRT Artificial sequence Synthetic 27 Gly Pro Arg Leu Leu Lys Glu Val Glu Glu Leu Glu Lys Lys Val Asp 1 5 10 15 Glu Leu Tyr Lys Ile Val Glu His Gly 20 25 28 2477 PRT Homo sapien 28 Met Asp Pro Ser Gly Val Lys Val Leu Glu Thr Ala Glu Asp Ile Gln 1 5 10 15 Glu Arg Arg Gln Gln Val Leu Asp Arg Tyr His Arg Phe Lys Glu Leu 20 25 30 Ser Thr Leu Arg Arg Gln Lys Leu Glu Asp Ser Tyr Arg Phe Gln Phe 35 40 45 Phe Gln Arg Asp Ala Glu Glu Leu Glu Lys Trp Ile Gln Glu Lys Leu 50 55 60 Gln Ile Ala Ser Asp Glu Asn Tyr Lys Asp Pro Thr Asn Leu Gln Gly 65 70 75 80 Lys Leu Gln Lys His Gln Ala Phe Glu Ala Glu Val Gln Ala Asn Ser 85 90 95 Gly Ala Ile Val Lys Leu Asp Glu Thr Gly Asn Leu Met Ile Ser Glu 100 105 110 Gly His Phe Ala Ser Glu Thr Ile Arg Thr Arg Leu Met Glu Leu His 115 120 125 Arg Gln Trp Glu Leu Leu Leu Glu Lys Met Arg Glu Lys Gly Ile Lys 130 135 140 Leu Leu Gln Ala Gln Lys Leu Val Gln Tyr Leu Arg Glu Cys Glu Asp 145 150 155 160 Val Met Asp Trp Ile Asn Asp Lys Glu Ala Ile Val Thr Ser Glu Glu 165 170 175 Leu Gly Gln Asp Leu Glu His Val Glu Val Leu Gln Lys Lys Phe Glu 180 185 190 Glu Phe Gln Thr Asp Met Ala Ala His Glu Glu Arg Val Asn Glu Val 195 200 205 Asn Gln Phe Ala Ala Lys Leu Ile Gln Glu Gln His Pro Glu Glu Glu 210 215 220 Leu Ile Lys Thr Lys Gln Asp Glu Val Asn Ala Ala Trp Gln Arg Leu 225 230 235 240 Lys Gly Leu Ala Leu Gln Arg Gln Gly Lys Leu Phe Gly Ala Ala Glu 245 250 255 Val Gln Arg Phe Asn Arg Asp Val Asp Glu Thr Ile Ser Trp Ile Lys 260 265 270 Glu Lys Glu Gln Leu Met Ala Ser Asp Asp Phe Gly Arg Asp Leu Ala 275 280 285 Ser Val Gln Ala Leu Leu Arg Lys His Glu Gly Leu Glu Arg Asp Leu 290 295 300 Ala Ala Leu Glu Asp Lys Val Lys Ala Leu Cys Ala Glu Ala Asp Arg 305 310 315 320 Leu Gln Gln Ser His Pro Leu Ser Ala Thr Gln Ile Gln Val Lys Arg 325 330 335 Glu Glu Leu Ile Thr Asn Trp Glu Gln Ile Arg Thr Leu Ala Ala Glu 340 345 350 Arg His Ala Arg Leu Asn Asp Ser Tyr Arg Leu Gln Arg Phe Leu Ala 355 360 365 Asp Phe Arg Asp Leu Thr Ser Trp Val Thr Glu Met Lys Ala Leu Ile 370 375 380 Asn Ala Asp Glu Leu Ala Ser Asp Val Ala Gly Ala Glu Ala Leu Leu 385 390 395 400 Asp Arg His Gln Glu His Lys Gly Glu Ile Asp Ala His Glu Asp Ser 405 410 415 Phe Lys Ser Ala Asp Glu Ser Gly Gln Ala Leu Leu Ala Ala Gly His 420 425 430 Tyr Ala Ser Asp Glu Val Arg Glu Lys Leu Thr Val Leu Ser Glu Glu 435 440 445 Arg Ala Ala Leu Leu Glu Leu Trp Glu Leu Arg Arg Gln Gln Tyr Glu 450 455 460 Gln Cys Met Asp Leu Gln Leu Phe Tyr Arg Asp Thr Glu Gln Val Asp 465 470 475 480 Asn Trp Met Ser Lys Gln Glu Ala Phe Leu Leu Asn Glu Asp Leu Gly 485 490 495 Asp Ser Leu Asp Ser Val Glu Ala Leu Leu Lys Lys His Glu Asp Phe 500 505 510 Glu Lys Ser Leu Ser Ala Gln Glu Glu Lys Ile Thr Ala Leu Asp Glu 515 520 525 Phe Ala Thr Lys Leu Ile Gln Asn Asn His Tyr Ala Met Glu Asp Val 530 535 540 Ala Thr Arg Arg Asp Ala Leu Leu Ser Arg Arg Asn Ala Leu His Glu 545 550 555 560 Arg Ala Met Arg Arg Arg Ala Gln Leu Ala Asp Ser Phe His Leu Gln 565 570 575 Gln Phe Phe Arg Asp Ser Asp Glu Leu Lys Ser Trp Val Asn Glu Lys 580 585 590 Met Lys Thr Ala Thr Asp Glu Ala Tyr Lys Asp Pro Ser Asn Leu Gln 595 600 605 Gly Lys Val Gln Lys His Gln Ala Phe Glu Ala Glu Leu Ser Ala Asn 610 615 620 Gln Ser Arg Ile Asp Ala Leu Glu Lys Ala Gly Gln Lys Leu Ile Asp 625 630 635 640 Val Asn His Tyr Ala Lys Asp Glu Val Ala Ala Arg Met Asn Glu Val 645 650 655 Ile Ser Leu Trp Lys Lys Leu Leu Glu Ala Thr Glu Leu Lys Gly Ile 660 665 670 Lys Leu Arg Glu Ala Asn Gln Gln Gln Gln Phe Asn Arg Asn Val Glu 675 680 685 Asp Ile Glu Leu Trp Leu Tyr Glu Val Glu Gly His Leu Ala Ser Asp 690 695 700 Asp Tyr Gly Lys Asp Leu Thr Asn Val Gln Asn Leu Gln Lys Lys His 705 710 715 720 Ala Leu Leu Glu Ala Asp Val Ala Ala His Gln Asp Arg Ile Asp Gly 725 730 735 Ile Thr Ile Gln Ala Arg Gln Phe Gln Asp Ala Gly His Phe Asp Ala 740 745 750 Glu Asn Ile Lys Lys Lys Gln Glu Ala Leu Val Ala Arg Tyr Glu Ala 755 760 765 Leu Lys Glu Pro Met Val Ala Arg Lys Gln Lys Leu Ala Asp Ser Leu 770 775 780 Arg Leu Gln Gln Leu Phe Arg Asp Val Glu Asp Glu Glu Thr Trp Ile 785 790 795 800 Arg Glu Lys Glu Pro Ile Ala Ala Ser Thr Asn Arg Gly Lys Asp Leu 805 810 815 Ile Gly Val Gln Asn Leu Leu Lys Lys His Gln Ala Leu Gln Ala Glu 820 825 830 Ile Ala Gly His Glu Pro Arg Ile Lys Ala Val Thr Gln Lys Gly Asn 835 840 845 Ala Met Val Glu Glu Gly His Phe Ala Ala Glu Asp Val Lys Ala Lys 850 855 860 Leu His Glu Leu Asn Gln Lys Trp Glu Ala Leu Lys Ala Lys Ala Ser 865 870 875 880 Gln Arg Arg Gln Asp Leu Glu Asp Ser Leu Gln Ala Gln Gln Tyr Phe 885 890 895 Ala Asp Ala Asn Glu Ala Glu Ser Trp Met Arg Glu Lys Glu Pro Ile 900 905 910 Val Gly Ser Thr Asp Tyr Gly Lys Asp Glu Asp Ser Ala Glu Ala Leu 915 920 925 Leu Lys Lys His Glu Ala Leu Met Ser Asp Leu Ser Ala Tyr Gly Ser 930 935 940 Ser Ile Gln Ala Leu Arg Glu Gln Ala Gln Ser Cys Arg Gln Gln Val 945 950 955 960 Ala Pro Thr Asp Asp Glu Thr Gly Lys Glu Leu Val Leu Ala Leu Tyr 965 970 975 Asp Tyr Gln Glu Lys Ser Pro Arg Glu Val Thr Met Lys Lys Gly Asp 980 985 990 Ile Leu Thr Leu Leu Asn Ser Thr Asn Lys Asp Trp Trp Lys Val Glu 995 1000 1005 Val Asn Asp Arg Gln Gly Phe Val Pro Ala Ala Tyr Val Lys Lys 1010 1015 1020 Leu Asp Pro Ala Gln Ser Ala Ser Arg Glu Asn Leu Leu Glu Glu 1025 1030 1035 Gln Gly Ser Ile Ala Leu Arg Gln Glu Gln Ile Asp Asn Gln Thr 1040 1045 1050 Arg Ile Thr Lys Glu Ala Gly Ser Val Ser Leu Arg Met Lys Gln 1055 1060 1065 Val Glu Glu Leu Tyr His Ser Leu Leu Glu Leu Gly Glu Lys Arg 1070 1075 1080 Lys Gly Met Leu Glu Lys Ser Cys Lys Lys Phe Met Leu Phe Arg 1085 1090 1095 Glu Ala Asn Glu Leu Gln Gln Trp Ile Asn Glu Lys Glu Ala Ala 1100 1105 1110 Leu Thr Ser Glu Glu Val Gly Ala Asp Leu Glu Gln Val Glu Val 1115 1120 1125 Leu Gln Lys Lys Phe Asp Asp Phe Gln Lys Asp Leu Lys Ala Asn 1130 1135 1140 Glu Ser Arg Leu Lys Asp Ile Asn Lys Val Ala Glu Asp Leu Glu 1145 1150 1155 Ser Glu Gly Leu Met Ala Glu Glu Val Gln Ala Val Gln Gln Gln 1160 1165 1170 Glu Val Tyr Gly Met Met Pro Arg Asp Glu Thr Asp Ser Lys Thr 1175 1180 1185 Ala Ser Pro Trp Lys Ser Ala Arg Leu Met Val His Thr Val Ala 1190 1195 1200 Thr Phe Asn Ser Ile Lys Glu Leu Asn Glu Arg Trp Arg Ser Leu 1205 1210 1215 Gln Gln Leu Ala Glu Glu Arg Ser Gln Leu Leu Gly Ser Ala His 1220 1225 1230 Glu Val Gln Arg Phe His Arg Asp Ala Asp Glu Thr Lys Glu Trp 1235 1240 1245 Ile Glu Glu Lys Asn Gln Ala Leu Asn Thr Asp Asn Tyr Gly His 1250 1255 1260 Asp Leu Ala Ser Val Gln Ala Leu Gln Arg Lys His Glu Gly Phe 1265 1270 1275 Glu Arg Asp Leu Ala Ala Leu Gly Asp Lys Val Asn Ser Leu Gly 1280 1285 1290 Glu Thr Ala Glu Arg Leu Ile Gln Ser His Pro Glu Ser Ala Glu 1295 1300 1305 Asp Leu Gln Glu Lys Cys Thr Glu Leu Asn Gln Ala Trp Ser Ser 1310 1315 1320 Leu Gly Lys Arg Ala Asp Gln Arg Lys Ala Lys Leu Gly Asp Ser 1325 1330 1335 His Asp Leu Gln Arg Phe Leu Ser Asp Phe Arg Asp Leu Met Ser 1340 1345 1350 Trp Ile Asn Gly Ile Arg Gly Leu Val Ser Ser Asp Glu Leu Ala 1355 1360 1365 Lys Asp Val Thr Gly Ala Glu Ala Leu Leu Glu Arg His Gln Glu 1370 1375 1380 His Arg Thr Glu Ile Asp Ala Arg Ala Gly Thr Phe Gln Ala Phe 1385 1390 1395 Glu Gln Phe Gly Gln Gln Leu Leu Ala His Gly His Tyr Ala Ser 1400 1405 1410 Pro Glu Ile Lys Gln Lys Leu Asp Ile Leu Asp Gln Glu Arg Ala 1415 1420 1425 Asp Leu Glu Lys Ala Trp Val Gln Arg Arg Met Met Leu Asp Gln 1430 1435 1440 Cys Leu Glu Leu Gln Leu Phe His Arg Asp Cys Glu Gln Ala Glu 1445 1450 1455 Asn Trp Met Ala Ala Arg Glu Ala Phe Leu Asn Thr Glu Asp Lys 1460 1465 1470 Gly Asp Ser Leu Asp Ser Val Glu Ala Leu Ile Lys Lys His Glu 1475 1480 1485 Asp Phe Asp Lys Ala Ile Asn Val Gln Glu Glu Lys Ile Ala Ala 1490 1495 1500 Leu Gln Ala Phe Ala Asp Gln Leu Ile Ala Ala Gly His Tyr Ala 1505 1510 1515 Lys Gly Asp Ile Ser Ser Arg Arg Asn Glu Val Leu Asp Arg Trp 1520 1525 1530 Arg Arg Leu Lys Ala Gln Met Ile Glu Lys Arg Ser Lys Leu Gly 1535 1540 1545 Glu Ser Gln Thr Leu Gln Gln Phe Ser Arg Asp Val Asp Glu Ile 1550 1555 1560 Glu Ala Trp Ile Ser Glu Lys Leu Gln Thr Ala Ser Asp Glu Ser 1565 1570 1575 Tyr Lys Asp Pro Thr Asn Ile Gln Leu Ser Lys Leu Leu Ser Lys 1580 1585 1590 His Gln Lys His Gln Ala Phe Glu Ala Glu Leu His Ala Asn Ala 1595 1600 1605 Asp Arg Ile Arg Gly Val Ile Asp Met Gly Asn Ser Leu Ile Glu 1610 1615 1620 Arg Gly Ala Cys Ala Gly Ser Glu Asp Ala Val Lys Ala Arg Leu 1625 1630 1635 Ala Ala Leu Ala Asp Gln Trp Gln Phe Leu Val Gln Lys Ser Ala 1640 1645 1650 Glu Lys Ser Gln Lys Leu Lys Glu Ala Asn Lys Gln Gln Asn Phe 1655 1660 1665 Asn Thr Gly Ile Lys Asp Phe Asp Phe Trp Leu Ser Glu Val Glu 1670 1675 1680 Ala Leu Leu Ala Ser Glu Asp Tyr Gly Lys Asp Leu Ala Ser Val 1685 1690 1695 Asn Asn Leu Leu Lys Lys His Gln Leu Leu Glu Ala Asp Ile Ser 1700 1705 1710 Ala His Glu Asp Arg Leu Lys Asp Leu Asn Ser Gln Ala Asp Ser 1715 1720 1725 Leu Met Thr Ser Ser Ala Phe Asp Thr Ser Gln Val Lys Asp Lys 1730 1735 1740 Arg Asp Thr Ile Asn Gly Arg Phe Gln Lys Ile Lys Ser Met Ala 1745 1750 1755 Ala Ser Arg Arg Ala Lys Leu Asn Glu Ser His Arg Leu His Gln 1760 1765 1770 Phe Phe Arg Asp Met Asp Asp Glu Glu Ser Trp Ile Lys Glu Lys 1775 1780 1785 Lys Leu Leu Val Gly Ser Glu Asp Tyr Gly Arg Asp Leu Thr Gly 1790 1795 1800 Val Gln Asn Leu Arg Lys Lys His Lys Arg Leu Glu Ala Glu Leu 1805 1810 1815 Ala Ala His Glu Pro Ala Ile Gln Gly Val Leu Asp Thr Gly Lys 1820 1825 1830 Lys Leu Ser Asp Asp Asn Thr Ile Gly Lys Glu Glu Ile Gln Gln 1835 1840 1845 Arg Leu Ala Gln Phe Val Glu His Trp Lys Glu Leu Lys Gln Leu 1850 1855 1860 Ala Ala Ala Arg Gly Gln Arg Leu Glu Glu Ser Leu Glu Tyr Gln 1865 1870 1875 Gln Phe Val Ala Asn Val Glu Glu Glu Glu Ala Trp Ile Asn Glu 1880 1885 1890 Lys Met Thr Leu Val Ala Ser Glu Asp Tyr Gly Asp Thr Leu Ala 1895 1900 1905 Ala Ile Gln Gly Leu Leu Lys Lys His Glu Ala Phe Glu Thr Asp 1910 1915 1920 Phe Thr Val His Lys Asp Arg Val Asn Asp Val Cys Thr Asn Gly 1925 1930 1935 Gln Asp Leu Ile Lys Lys Asn Asn His His Glu Glu Asn Ile Ser 1940 1945 1950 Ser Lys Met Lys Gly Leu Asn Gly Lys Val Ser Asp Leu Glu Lys 1955 1960 1965 Ala Ala Ala Gln Arg Lys Ala Asn Val Asp Glu Asn Ser Ala Phe 1970 1975 1980 Leu Gln Phe Asn Trp Lys Ala Asp Val Val Glu Ser Trp Ile Gly 1985 1990 1995 Glu Lys Glu Asn Ser Leu Lys Thr Asp Asp Tyr Gly Arg Asp Leu 2000 2005 2010 Ser Ser Val Gln Thr Leu Leu Thr Lys Gln Glu Thr Phe Asp Ala 2015 2020 2025 Gly Leu Gln Ala Phe Gln Gln Glu Gly Ile Ala Asn Ile Thr Ala 2030 2035 2040 Leu Lys Asp Gln Leu Leu Ala Ala Lys His Val Gln Ser Lys Ala 2045 2050 2055 Ile Glu Ala Arg His Ala Ser Leu Met Lys Arg Trp Ser Gln Leu 2060 2065 2070 Leu Ala Asn Ser Ala Ala Arg Lys Lys Lys Leu Leu Glu Ala Gln 2075 2080 2085 Ser His Phe Arg Lys Val Glu Asp Leu Phe Leu Thr Phe Ala Lys 2090 2095 2100 Lys Ala Ser Ala Phe Asn Ser Trp Phe Glu Asn Ala Glu Glu Asp 2105 2110 2115 Leu Thr Asp Pro Val Arg Cys Asn Ser Leu Glu Glu Ile Lys Ala 2120 2125 2130 Leu Arg Glu Ala His Asp Ala Phe Arg Ser Ser Leu Ser Ser Ala 2135 2140 2145 Gln Ala Asp Phe Asn Gln Leu Ala Glu Leu Asp Arg Gln Ile Lys 2150 2155 2160 Ser Phe Arg Val Ala Ser Asn Pro Tyr Thr Trp Phe Thr Met Glu 2165 2170 2175 Ala Leu Glu Glu Thr Trp Arg Asn Leu Gln Lys Ile Ile Lys Glu 2180 2185 2190 Arg Glu Leu Glu Leu Gln Lys Glu Gln Arg Arg Gln Glu Glu Asn 2195 2200 2205 Asp Lys Leu Arg Gln Glu Phe Ala Gln His Ala Asn Ala Phe His 2210 2215 2220 Gln Trp Ile Gln Glu Thr Arg Thr Tyr Leu Leu Asp Gly Ser Cys 2225 2230 2235 Met Val Glu Glu Ser Gly Thr Leu Glu Ser Gln Leu Glu Ala Thr 2240 2245 2250 Lys Arg Lys His Gln Glu Ile Arg Ala Met Arg Ser Gln Leu Lys 2255 2260 2265 Lys Ile Glu Asp Leu Gly Ala Ala Met Glu Glu Ala Leu Ile Leu 2270 2275 2280 Asp Asn Lys Tyr Thr Glu His Ser Thr Val Gly Leu Ala Gln Gln 2285 2290 2295 Trp Asp Gln Leu Asp Gln Leu Gly Met Arg Met Gln His Asn Leu 2300 2305 2310 Glu Gln Gln Ile Gln Ala Arg Asn Thr Thr Gly Val Thr Glu Glu 2315 2320 2325 Ala Leu Lys Glu Phe Ser Met Met Phe Lys His Phe Asp Lys Asp 2330 2335 2340 Lys Ser Gly Arg Leu Asn His Gln Glu Phe Lys Ser Cys Leu Arg 2345 2350 2355 Ser Leu Gly Tyr Asp Leu Pro Met Val Glu Glu Gly Glu Pro Asp 2360 2365 2370 Pro Glu Phe Glu Ala Ile Leu Asp Thr Val Asp Pro Asn Arg Asp 2375 2380 2385 Gly His Val Ser Leu Gln Glu Tyr Met Ala Phe Met Ile Ser Arg 2390 2395 2400 Glu Thr Glu Asn Val Lys Ser Ser Glu Glu Ile Glu Ser Ala Phe 2405 2410 2415 Arg Ala Leu Ser Ser Glu Gly Lys Pro Tyr Val Thr Lys Glu Glu 2420 2425 2430 Leu Tyr Gln Asn Leu Thr Arg Glu Gln Ala Asp Tyr Cys Val Ser 2435 2440 2445 His Met Lys Pro Tyr Val Asp Gly Lys Gly Arg Glu Leu Pro Thr 2450 2455 2460 Ala Phe Asp Tyr Val Glu Phe Thr Arg Ser Leu Phe Val Asn 2465 2470 2475 29 8 PRT Artificial sequence Synthetic 29 Gly Ser Gly Ile Glu Gly Arg Met 1 5 

What is claimed is:
 1. A composition comprising a pair of antibody Fv fragments linked and stabilized by antiparallel heterogeneous α-helical coiled-coil (AHEC) peptides.
 2. The composition of claim 1 wherein the AHEC peptides form dimeric α-helical coiled-coil complexes.
 3. The composition of claim 1 wherein the AHEC peptides form trimeric α-helical coiled-coil complexes.
 4. The composition of claim 1 wherein the AHEC peptides form tetrameric α-helical coiled-coil complexes.
 5. The composition of claim 2 wherein the AHEC peptides comprise α-helical coils specifically designed de novo.
 6. The composition of claim 3 wherein the AHEC peptides comprise α-helical coils derived from repeat domains of the spectrin family proteins.
 7. The composition of claim 3 wherein the AHEC peptides comprise α-helical coils specifically designed de novo.
 8. The composition of claim 4 wherein the AHEC peptides comprise α-helical coils specifically designed de novo.
 9. The composition of claims 3 through 4 and 6 through 8 further comprising a protein, protein fragment, peptide or chemical linked to one or more of the AHEC peptides.
 10. The composition of claim 3 through 4 and 6 through 8 further comprising an inert molecule.
 11. The composition of claim 9 wherein the inert molecule comprises poly(ethylene glycol).
 12. An immobilized multimeric protein comprising the composition of claim 1 immobilized to a solid support via the AHEC peptides wherein one of the peptides forming the AHEC is linked to the solid support.
 13. A method for stabilizing and assembling a pair of antibody Fv fragments into a multimeric complex comprising linking the pair of antibody Fv fragment via their C termini with antiparallel heterogeneous α-helical coiled-coil (AHEC) peptides.
 14. The method of claim 13 wherein the AHEC peptides form trimeric α-helical coiled-coil complexes or tetrameric α-helical coiled-coil complexes.
 15. The method of claim 14 further comprising linking a protein, protein fragment, peptide or chemical to the multimeric complex via one or more of the AHEC peptides. 